D+C Schengen visa

I am a Hong Kong exchange student in Austria. I have some enquires about the access to schengen with my visa and passport.

The passport I hold is Hong Kong SAR passport.
The schengen visa I got is a kind of D+C visa.
It said, " A+ Schengen Staaten".
It is valid from 2nd March to 20 July 2009.
The Austrian embassy told me I can travel or pass through
all schengen countries with free access with this visa for the FIRST 90dDAYS only.
If I need to go to other schengenan countries other than Austria, I should apply for a separate visa.

My flight back to Hong Kong requires passing through Frankfurt
in Germany.
In this way, I need to get a separate visa which costs 60 Euro.


My enquiry is that I dont understand why there is so unconvenient policy on Hong Kong students with HKSAR passport!!!

60 Euro for just a airport transit is too expensive for a student.
And we need travelling to widen horizon, but not just studying studying studying...=.="

I would like to ask if I still can get 3 months visa-free access to Schengen countries when I leave Austria to UK for several days.

I mean I plan to leave Austria to non-schengen countries like UK and wondering if I can have 3 months visa-free travelling in Schengen,
because I know Hong Kong citizen with SAR passport are offered 90 days visa-free travelling.

Thz so much if anyone at least can suggest me wht to do~~